General Description of Services

Offering services for: High quality peptide synthesis, peptide arrays and microarrays, and peptide library synthesis


Peptide Synthesis:

Generally four levels of peptide purity are available, with each level of purity serving a different application:

  1. Crude peptides (without analytical data unless separately ordered)
  2. Desalted peptides (purity usually 50-70%, RP-HPLC profile and MS data will be provided)
  3. >80% HPLC-purified peptides (analytical RP-HPLC profile and MS data will be provided)
  4. >95% HPLC-purified peptides (analytical RP-HPLC profile and MS data will be provided).

All peptides after cleavage from resins are pre-purified by precipitation, washing with organic solvent and lyophilization. Both crude and purified peptides are delivered as lyophilized powders. The turn-around time generally is 1-2 weeks for crude peptides and 2-3 weeks for purified peptides. There are four synthesis scales to choose from: 10, 25, 50, and 100 µmol (if need large scale synthesis please contact us). For each of these scales, the peptide can be obtained either in crude, desalted, or purified form. MAPs are available in crude or desalted form.

Typical applications of synthetic peptides at various purity levels:

Crude and “desalted” peptides are usually used for high-throughput screening (e.g. preliminary screening of large number of peptides for lead generation). Desalted peptides are preferred when salts can interfere with the assay or when good estimation of peptide concentration is needed.

  • >80% pure peptides are used as antigens for antibody production, purification, and blocking, as ligands for affinity purification, in enzyme substrate studies, epitope mapping, ELISA, and bioassays
  • >95% pure peptides are usually used in quantitative bioassays, as enzyme substrates/inhibitors in quantitative studies, markers for electrophoresis, chromatography standards, in NMR, ELISA, crystallization, ITC, and SAR studies

The ranges of expected yields for each scale and purity level are given in the table.

Synthesis ScaleRange of typical yields (mg)Expected yields of 20-mer peptide (mg)
(in µmol)
Crude
Peptide
Desalted
Peptide
Purity
>80%
Purity
>95%
Crude
Peptide
Desalted
Peptide
Purity
>80%
Purity
>95%

10 µmol

3-15

2-7

1-6

0.5-3

~7

~5

~2

~1

25 µmol

10-30

6-20

2-15

1-10

~20

~15

~10

~8

50 µmol

20-60

12-40

4-30

2-20

~40

~30

~20

~15

100 µmol

40-120

25-80

10-60

4-40

~80

~60

~40

~30

 

Peptide purity should not be confused with peptide content. For example, 100% pure peptide, after lyophilization contains water (usually 3-10%), trifluoroacetate or acetate counterions,  and may also contain residual TFA. Peptides are usually hygroscopic and water content increases during storage and handling.

Synthesis of Peptides Containing Modified Amino Acids:

We can incorporate a wide range of modified amino acids into synthetic peptides. The primary limitation is the commercial availability of required Fmoc-amino acid derivatives. Since incorporation of modified amino acids often will increase the difficulty of peptide synthesis, this may lead to lower yields or purity of the product.  In some instances the complications of incorporating the unusual amino acid can be minimized by its position in the peptide sequence. Usually preferred positions for modified residues are those close to N-terminus of the peptide sequence (especially for phospho-amino acid and trimethyl-lysine residues). The incorporation of modified amino acids in the peptide will also result in additional charges, usually the price of Fmoc derivative of the modified amino acid (please contact us for details).

MAPs:

Multiple Antigenic Peptides (MAPs) offer an alternative approach to for raising antibodies using synthetic peptides. Peptide epitopes attached to a 4 or 8 branching core (the core of 3 or 7 Lys residues) result in three dimensional molecules with highly localized epitope density and no additional peptide sequences. MAPs (molecular size between 5 and 15 kDa) are suitable for direct antibody production without the need to couple to a carrier protein. Multiple copies of antigen epitopes in MAPs have been shown to produce strong immunogenic response (see References 6 and 7).

Synthesis of Peptide Libraries:

We can help in the design of a peptide library.  We can synthesize the library of ≤120 crude peptides within 2-3 weeks, for larger libraries we need 2 additional weeks per 120 peptides. The peptides are delivered as lyophilized powders in separate vials or as lyophilized aliquots in eppendorf tubes (additional fee). The quality of 1/12 of library peptides is checked by MS and RP HPLC.  We can check the quality of other library peptides at users request for additional fee (see price list).

Printing of Peptide Microarrays:

We have experience in printing peptide microarrays from synthetic peptide libraries (see Ref. 3-5) using the GeneMachines OmniGrid 100 arrayer. The arrayer can print up to ~4000 spots per microscopic slide (up to 20 slides per run). One run takes up to 8 hours, depending on array configuration, number of samples, spots, and slides. The samples are printed from 384-well plate.

Acknowledging the HTPSA Core Facility:

Please acknowledge use of the HTPSA Core Facility in your presentations and publications. This will help us demonstrate the Core Facility’s value for the local scientific community.

Example of acknowledgment:

Peptide(s) synthesis was performed in the High-Throughput Peptide Synthesis and Arrays Core Facility at University of North Carolina in Chapel Hill. North Carolina Biotechnology Center Institutional Development Grant provided funding to develop this facility.